fix: fieldvalue gettimestamp (#279)

Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly: - [X] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/java-bigquery/issues/new/choose) before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea - [X] Ensure the tests and linter pass - [X] Code coverage does not decrease (if any source code was changed) - [X] Appropriate docs were updated (if necessary) Fixes #16

Author: Praful Makani

google-cloud-bigquery/src/main/java/com/google/cloud/bigquery/FieldValue.java

@@ -182,7 +182,9 @@ public boolean getBooleanValue() {
  public long getTimestampValue() {
  // timestamps are encoded in the format 1408452095.22 where the integer part is seconds since
  // epoch (e.g. 1408452095.22 == 2014-08-19 07:41:35.220 -05:00)
- return new Double(Double.valueOf(getStringValue()) * MICROSECONDS).longValue();
+ BigDecimal secondsWithMicro = new BigDecimal(getStringValue());
+ BigDecimal scaled = secondsWithMicro.scaleByPowerOfTen(6);
+ return scaled.longValue();
  }
 
  /**

google-cloud-bigquery/src/test/java/com/google/cloud/bigquery/FieldValueTest.java

@@ -89,6 +89,14 @@ public void testFromPb() {
  assertEquals(FieldValue.fromPb(TIMESTAMP_FIELD), value.getRepeatedValue().get(1));
  }
 
+ @Test
+ public void testTimestamp() {
+ FieldValue fieldValue = FieldValue.of(FieldValue.Attribute.PRIMITIVE, "-1.9954383398377106E10");
+ long received = fieldValue.getTimestampValue();
+ long expected = -19954383398377106L;
+ assertEquals(expected, received);
+ }
+
  @Test
  public void testEquals() {
  FieldValue booleanValue = FieldValue.of(FieldValue.Attribute.PRIMITIVE, "false");